Quality control systems provide a significant demand for quick connect couplings. In this regard, quick connect couplings are often used to facilitate testing manufactured products for leaks. In use, the couplings provide a quick connection to test pieces such as products that hold a fluid or products designed to work under pressure or vacuum. Once the connection is made, a test fluid is communicated through the coupling to the test piece to determine if the test piece has any leaks. In order to maximize production efficiency, it is important that the couplings provide fast and reliable seals.
U.S. Pat. No. 4,716,938 to Weh et al. discloses a pressure tight plug coupling having a split collet design. The coupling includes a cylindrical housing and a piston shiftably mounted within the housing. The piston includes exterior clamping jaws that cooperate with an expansion member to move the clamping jaws radially inward or outward. The expansion member extends longitudinally through the entire length of the cylindrical housing and is connected to a rear side of the housing. The arrangement of the expansion member creates a flow path within the coupling that must be sealed by an internal sealing member.
An additional plug coupling utilizing a split collet design is disclosed in WO 89/07729. This coupling includes a housing, and a piston slideably mounted in the housing. A split collet assembly is connected to the piston for movement therewith, and the end of the split collet assembly is expanded by an expansion member extending through the split collet assembly and the piston. Expansion is caused by angled ramp surfaces on the expansion member and the end of the split collet assembly. The expansion member is connected to an actuating member, whereby the expansion member is axially shifted to permit contraction of the end of the split collet assembly. The design of the coupling is such that when the split collet assembly is expanded, the angled surfaces of the expansion member and the split collet assembly are not engaged. Therefore the entire force of the pressurized fluid acting on the expansion member is transferred axially down the expansion member.
What is needed is an improved plug coupling that has a more durable design allowing higher pressures, allows pressure to vent prior to the collets disconnecting from the fluid port, and which is simple to operate.